Organic polymers containing at least one reactive silyl group in each molecule are known to have properties such that they are cross-linked by siloxane bond formation involving reactions such as hydrolysis of the reactive silyl group due to moisture or the like even at room temperature, and thereby provide rubbery cured products.
Among these reactive silyl group-containing polymers, those polymers which have a main chain skeleton of a polyoxyalkylene polymer or a polyisobutylene polymer are disclosed in Patent Documents 1 and 2, and the like. These polymers have already been industrially produced and used in various applications such as sealants, adhesives, and coatings.
Curable compositions containing these reactive silyl group-containing organic polymers further contain a silanol condensation catalyst in order to provide cured products. Common examples of the silanol condensation catalyst include organotin catalysts having a carbon-tin bond, such as dibutyltin bis(acetylacetonate) and dibutyltin dilaurate. In recent years, however, organotin compounds are known to be toxic, and the development of non-organotin catalysts has been desired.
Patent Documents 3, 4, 5, 6, and 7 disclose tin carboxylates and other metal carboxylates as silanol condensation catalysts.
These documents also disclose that addition of an amine compound as a promoter to such catalysts improves curability. In consideration of environmental load, a curing catalyst containing substantially no metal is also desired. Patent Document 8 discloses that combination use of an amine compound and a carboxylic acid provides a metal-free silanol condensation catalyst.
As above, combination use of an amine compound and another silanol condensation catalyst is a known technique to improve curability. With this technique, however, the adhesiveness in the case of using the non-organotin catalysts disclosed by the above Patent Documents needs to be further improved compared to the case of using organotin catalysts.
There are very few documents disclosing an example that an amine compound is solely used as a silanol condensation catalyst. Although Patent Document 9 discloses a technique with use of a biguanide compound, which is one of amine compounds, as a silanol condensation catalyst, it has a problem that the curable composition may not show practical curability.
Patent Documents 10 and 11 each disclose a technique in which a highly active reactive silyl group is used in combination so that the above curability problem is solved. Further, Patent Document 12 teaches that a guanidine compound having a specific structure has specifically high catalytic activity and provides good adhesiveness. However, those biguanide compounds and guanidine compounds have a problem that the resulting cured products have yellowing on the surface after a long time or have not only discoloration but also cracks (fractures) on the surface when exposed outdoors, differently from the case of using commonly used organnotin catalysts.
Meanwhile, phosphorus compounds are generally used as plasticizers, antioxidants, antifungal agents, and flame retardants for polymer materials, and are disclosed for example by Patent Document 13. Patent Document 14 discloses an antibacterial sealant composition containing a cyclic phosphate ester compound together with a reactive silyl group-containing organic polymer.
Patent Document 1: JP-A S52-73998
Patent Document 2: JP-A S63-6041
Patent Document 3: JP-A H5-39428
Patent Document 4: JP-A H9-12860
Patent Document 5: JP-A 0.2000-313814
Patent Document 6: JP-A 2000-345054
Patent Document 7: JP-A 2003-206410
Patent Document 8: JP-A H5-117519
Patent Document 9: JP-A 2005-248175
Patent Document 10: WO 2007/094274
Patent Document 11: WO 2007/094275
Patent Document 12: WO 2007/094276
Patent Document 13: JP-A S61-174287
Patent Document 14: JP-B 3960650